2a87. VANOS solenoids & carbon buildup. I usually get in trouble trying to follow a handful of (faster) P-cars. This time around it was an RS. I was able to finish entire 25min sessions with the same settings and same ambient provided I'm ahead of the pack/not following anybody. Quite frustrating if you ask me...

Peter, have you installed the stett oil cooler? I'm curious to see what this mod did, also, try running with the heater on, like set to 78-80+, maybe fan setting on 3. This will make your oil temps take a dive.